The field of the invention is inhalers for delivering dry powder pharmaceuticals to the lungs.
Inhalers have long been used to deliver pharmaceuticals into a patient's lungs. Dry powder inhalers provide a mixture of a dry powder pharmaceutical and air to the patient. The air/pharmaceutical powder mixture is delivered via the patient inhaling from a mouthpiece on the inhaler. The Spiros.RTM. inhaler, described in U.S. Pat. Nos. 5,327,883 and 5,577,497, and U.S. Pat. Nos. 5,921,237 and 6,116,238, all incorporated herein by reference, hold great potential for improved delivery of dry powder pharmaceuticals to the lungs. These inhalers use a small electric motor which spins a propeller within an aerosolizing chamber. The spinning propeller efficiently mixes the air and powder pharmaceutical in the aerosolizing chamber, and also helps to separate the active drug particles from inactive carrier particles, increasing the respirable fraction of the pharmaceutical composition. However, the motor, batteries, switch, indicator lights, and related circuitry in these inhalers increase their manufacturing cost and complexity. Consequently, although these types of inhalers are greatly improved over prior inhalers and have performed very well in clinical tests, there remains a need for a dry powder inhaler having good efficiency yet with a simpler and less costly design.
Accordingly, it is an objection of the invention to provide a dry powder inhaler having the advantages of a propeller spinning within an aerosolizing chamber but with a simpler and less costly configuration than known inhalers.